1. Field of the Invention
The present invention relates generally to a zoom lens system incorporating a function to reduce a camera vibration and, more particularly, to a zoom lens system suitable for photography.
2. Related Background Art
In recent years, a variety of zoom lenses have been newly proposed. There have been also proposed a multiplicity of zoom lenses including a vibration reduction optical system for correcting an image blur due to vibrations of the zoom lens.
For instance, U.S. Pat. No. 5,069,537 discloses a method of stabilizing an image by way of an embodiment of a zoom lens constructed of two lens groups,. i.e., a first lens group having a negative refracting power and a second lens group having a positive refracting power.
According to the prior art disclosed in U.S. Pat. No. 5,069,537, there is presented nothing but the theoretical image stabilizing method aiming at the zoom lens in an intermediate telephoto range in which the focal length is approximately 100 mm or larger. Nothing about the characteristics of aberrations was absolutely elucidated based on a specific lens construction. Namely, the above prior art did not provide a zoom lens incorporating a desired imaging performance.
As described above, a small number of the conventional zoom lenses incorporating the function for reducing vibration exhibit a sufficient imaging performance. The disadvantage is that a still smaller number of zoom lenses have the function for reducing vibration and the imaging performance enough for use in the standard range particularly for 35 mm photos.